Even though sundials didn’t help much at night or on cloudy days, they were one of the most widespread methods of telling time. Since ancient Egypt, sundials use the sun’s altitude or position in the sky to mark daytime hours. They used a nodus, that is a slanted, pointed rod, which cast shadows along certain points of a dial to indicate hours. During the Renaissance period, sundials evolved into many shapes and types. After the introduction of clocks, sundials were still being referenced to reset clocks because of poor accuracy. The most common sundial is referred to as a “gnomon”, which can distinguish the time of day based on the shadow cast by the nodus.